This invention relates to disposable undergarments adapted for absorption and containment of excretion and more particularly to disposable undergarments such as a diaper, training pants, incontinence pants or the like.
Japanese Patent Application Publication No. 1996-24291A describes a disposable pants-type diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these two sheets so as to configure, in a longitudinal direction, a front waist region, a rear waist region and a crotch region extending between these two waist regions. The front and rear waist regions are connected to each other along transversely opposite side edge portion of these front and rear waist regions to define a waist-opening and a pair of leg-openings.
In the known diaper, the crotch region has a pair of transversely opposite side edge portions curving inward transversely to define peripheral edge portions of the respective leg-openings. The diaper is provided with a first elastic member attached under tension to the diaper so as to extend between front ends of the respective opposite side edge portions and to describe a circular arc which is convex rearward in the longitudinal direction and a second elastic member attached under tension to the diaper so as to extend between rear ends of the respective opposite side edge portions and to describe a circular arc which is convex forwardly in the longitudinal direction. The first and second elastic members respectively comprise side portions extending in the vicinity of the front and rear ends of the transversely opposite side edge portions and middle portions spaced in the longitudinal direction from each other and extending across the crotch region. Between the first and second elastic members, there are provided with a pair of third elastic members extending in the longitudinal direction along the transversely opposite side edge portions and bonded under tension to the diaper. The third elastic members intersect the middle portions of the first and second elastic members.
With this diaper put on the wearer""s body, the elastic members continuously extend along the peripheral edge portions of the respective leg-openings, so the wearer""s thighs are fully and tightly surrounded by the first-third elastic members although the first and second elastic members are spaced in the longitudinal direction from each other in the crotch region. Therefore, there is no anxiety that leakage of excretion might occur in the crotch region.
In the case of the diaper disclosed in the above-identified Publication, the third elastic members spaced in the transverse direction from each other in the crotch region rectilinearly extend along the transversely opposite side edge portions in the longitudinal direction. With a consequence, the third elastic members are not able to extend in a thigh-surrounding direction as the diaper is worn thereby to surround the wearer""s thighs. Thus, tensile stress of the third elastic members is not effective in the thigh-surrounding direction and efficiently used to fit the diaper around the wearer""s thighs.
In addition, zones of the transversely opposite side edge portions extending from the vicinity of respective branching points between the side portions and the middle portions to the vicinity of the front and rear ends are inevitably apt to be spaced apart from the wearer""s skin. These zones should be kept in close contact with the thighs using any effective means. However, none of such means is disclosed in the above-identified Publication.
It is an object of this invention to provide a disposable undergarment improved so that the tensile stress of the third elastic members may be adequately utilized to keep the above described zones of the transversely opposite side edge portions in close contact with the wearer""s thighs and to make the undergarment fit around the wearer""s thighs.
According to this invention, there is provided a disposable undergarment comprising a front waist region, a rear waist region and a crotch region extending between these waist regions, a pair of leg-openings defined at transversely opposite side edge portions of the crotch region, stretchable elastic members associated with the leg-openings which comprise a first elastic member extending substantially in a circular arc from a vicinity of respective front ends of the transversely opposite side edge portions rearward, a second elastic member extending substantially in a circular arc from a vicinity of respective rear ends of the transversely opposite side edge portions forward and third elastic members extending in the longitudinal direction along the transversely opposite side edge portions between the first and second elastic members.
The first elastic member has first both side portions extending in the vicinity of the respective front ends of the transversely opposite side edge portions and a first middle portion extending across the crotch region. The second elastic member has second both side portions extending in the vicinity of the rear ends of the transversely opposite side edge portions and a second middle portion spaced rearward in the longitudinal direction from the first middle portion by a given dimension and extending across the crotch region. The third elastic members respectively extend along the transversely opposite side edge portions so as to describe circular arcs which are convex inward and have first connecting portions extending from a vicinity of respective branching points between the first both side portions and the first middle portion and merged into the first both side portions and second connecting portions which extend from the vicinity of respective branching points between the second both side portions and the second middle portion and merged into the second both side portions
According to one preferred embodiment of this invention tensile stress of zones in which the first and second both side portions overlap the first and second connecting portions is higher than that of the remaining zone in which the first-third elastic members extend.
According to another preferred embodiment of this invention, the undergarment is a disposable diaper comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these sheets.
According to still another preferred embodiment of this invention, the undergarment is a disposable diaper comprising a liquid-absorbent panel including a liquid-absorbent core disposed between a liquid-pervious topsheet and a leak-barrier sheet, and a liquid-impervious backsheet defining the front and rear waist regions and the crotch region, the panel extending across the crotch region in the longitudinal direction and being joined to inner surface of the backsheet with the leak-barrier sheet lying therebetween, the first and second elastic members being attached to the backsheet, and the third elastic members are attached to transversely opposite side edge portions of the panel extending along the transversely opposite side edge portions of the crotch region.